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AIF2 Question for keystoneII TCI6638 that AIF2 can't support 5 link 20 Axc num?

cc_hrst
Prodigy 100 points

Dear TI engineer:

       Now My company's product based onTCI6638 chip. Recently we consider use AIF2 driver to receive LTE ant data. We need use AIF2 5 links and total
20 Axc num as receive and we don't need aif to send any data. The parameter set mainly reference to C6670 Ti Aif Tdd project. Please allow me to
tell the detail information about the aif and ddr config.
DDR3A-64bit-1333Mhz-2 link total 8Axc received buffer located in DDR3A
DDR3B-16bit-1333Mhz-1 link total 4Axc received buffer located in DDR3B
I want to add one or two link which located in DDR3A or DDR3B, but it failed to receive and even result to previous 3 links can't receive any data.
I attempt to adjust the ddr3 frequency to 2000Mhz, it can support more links, but it don't meet our product need which may result any other problem.
My Test project ony used aif2 and Queue Manager, there is not any other driver used to visit ddr memory. In addition, the product code must
contain other drvier such as dma which may visit ddr frequently. So the current config which support 3 links may be not support by product code.
So please help me to see what's the problem. It's very urgency for me and our product.
Please forgive me poor express.
Thank you very much!

  • 0
    TI__Guru* 81335 points

    Welcome to the TI E2E forum. I hope you will find many good answers here and in the TI.com documents and in the TI Wiki Pages (for processor issues). Be sure to search those for helpful information and to browse for the questions others may have asked on similar topics (e2e.ti.com). Please read all the links below my signature.

    We will get back to you on the above query shortly. Thank you for your patience.

  • 0
    TI__Mastermind 21025 points
    Hello,

    I have three responses:

    1) Your device is a Keystone2 6638, and you mentioned that your test project is based on a C6670 project. C6670 is a Keystone1 device, and the AIF2 LLDs are different between Keystone 1 and 2 - because the AIF2 is slightly changed in Keystone2, and the AIF2 SerDes is completely different. I'm surprised that anything is working. You should begin with an appropriate AIF2 example in the Keystone2 PDK.

    2) You don't mention the LTE Rate you are using. The AIF2 user guide for Keystone2 (SPRUHL2) specifies how many AxC are supported per link, given the desired LTE Rate. See Chapter 3, and Table 3-1.

    3) Increasing the DDR clock rate beyond 1333Mhz is not supported, and will not help anyway since there are other bottlenecks in the system.
  • 0 in reply to db_woodall
    Prodigy 100 points
    Hi db_woodall,
    I'm sorry that I have forgot to give more information.
    1) I have compared the aif2 specifies between Keystone1(c6670) and Keystone2(c6638) before transplant, there is slightly changed only serdes module. When I transplant the c6670 to c6638, I have changed the serdes module and use Keystone2's serdes config. So it can work well.
    2) LTE config as follows:
    LTE Rate Sample Rate Axc per Link = 8x CP
    20MHz 30.72MHz 4 Extended CP
    3)Now I find the main bottleneck is DDR clock rate but I don't think it is the essential reason, if I config 4 link and every link configs 4 axc, then Queue Manger can't place the axc data into ddr memory timely unless I add the DDR clock rate.

    In addition, on the C6670 evm board, the same LTE config can only support 3link 12axc num too.
  • 0 in reply to db_woodall
    Prodigy 100 points
    Hi db_woodall,

    This problem is very urgency to me, I can't find any other ways to solve this problem.
    On c6670 or c6638 EVM board，if aif‘s config as follow, how many links the aif can support?
    LTE config as follows:
    LTE Rate: 20MHz
    Sample Rate: 30.72MHz
    Axc per Link: 8x support max axcnum = 4
    Extended CP
    Receive Descriptor located to MSM
    Receive Axc Buffer located to DDR

    Regards,

    cc_hrst
  • 0 in reply to cc_hrst
    TI__Mastermind 21025 points

    Hello, sorry for the extended delay.  Perhaps we are approaching this backwards.  What is the throughput you are trying to achieve?  Section 7.1 of the user guide discusses peak bandwidth, with the bottleneck being the AIF2's Data Buffer (DB), meaning how much data can be held there waiting to be transmitted by the Packet DMA during peak times.  This happens when several AxC's occur close together (instead of spread out over time evenly).  Section 4.5.1.1 provides more information on this.

    I still think you are in for more problems by trying to port a Keystone 1 example to Keystone 2, rather than simply starting with a Keystone 2 example. There are other differences in the device, CSL and drivers that may cause problems.  I would recommend getting a single 8x LTE 20 link up and running, then add links until you encounter a problem, then examine the timing offsets of the AxCs.